Conventional four-stroke internal combustion engine will lose great inertia force due to reciprocative motion of piston moving between upper and lower dead points within the cylinder and may even affect the force balance of the engine. The force exerted during combustion and explosion in an engine may be reduced through the transmission from piston to crank shaft due to frictional force loss so that the engine efficiency will be decreased.
The present inventor has found the defects of conventional four-stroke engine and invented the present oscillating piston engine.